There are two problems with complaining.
First, it doesn’t work. You can complain about your company, your country or your friend’s cooking habits but nothing will change except you’ll end up wasting your time.
Second, complaining has a boomerang gist. When you get good at complaining, you start noticing evidence that makes your complaints even better. So you magnify that and plunge yourself in it, thus creating more situations worth quetching about. For you and the others.
Much better is to start taking actions that change the situations worth complaining about into the better ones. No matter how small the actions are.
Since they have the power to teach us something, situations worth complaining about are not bad, but certainly, complaining about them is.